The conception of nonlinear standing wave (NSW),which is produced by two beams with bi-directions in nonlinear medium,is proposed. The analytical formulas for power distribution,pitch and standing wave ratio of this NSW and phase shift of single-direction beam are deduced. The simulation results show,that when the nonlinearity is weak,the NSW power distribution maintains its cosine type,but there is a pitch modulation effect,which will be shorten when the power increases,and it is proportional to the geometric mean of maximum and minimum indices. When the nonlinearity is stronger,there are two nonlinear effects,including pitch modulation and waveform of NSW modulation effects,the distribution function curve of which is changed from cosine to periodic sharp pulses. The nonlinear phase shift is not proportional to distance,but it changes to periodic monotonic increasing function. The results of this paper are very important to nonlinear medium cavity of laser,frequency selected amplifier,multi-wavelength laser and other nonlinear optical devices.